The present invention relates to bezels and electromagnetic interference (xe2x80x9cEMIxe2x80x9d) shields for electronic devices, and, in particular, to features that partially fasten an EMI shield to a bezel, while also securing the bezel to an equipment enclosure.
Typically, electronic devices are housed in standardized equipment enclosures. Many equipment enclosures include an outer housing that is supported by an inner rack. The inner rack commonly comprises a substantially rectilinear metal frame including several vertical columns, each provided with a plurality of mounting and alignment holes that permit the mounting of various components to the inner rack.
Many equipment enclosures also include a removable bezel that forms an aesthetic front face for the enclosure. The bezel may also shield internal components from environmental contaminants, such as moisture and dust, as well as shield the environment from noise generated by components within the enclosure. Removing the bezel provides access to components mounted within the enclosures in order to repair, replace, inspect, and perform maintenance tasks on the components.
One current method used to fasten bezels to equipment enclosures employs a snap-on fastening mechanism. A snap-on design generally incorporates a series of snaps, which are either spaced around the edge of the front face of an equipment enclosure or around the perimeter of the interior lip of the bezel. Each snap is fastened to a corresponding retention-apparatus on the interlocking surface.
Many snap-on designs employ a series of retention-features, on the surface of the bezel, for snap retention. Each retention-feature must be molded as part of the bezel. Thus, every additional feature increases mold complexity and tooling-time expense. Consequently, molded bezels incorporating a snap-on fastening mechanism are expensive and time-consuming to manufacture.
Many electronic components generate electromagnetic radiation in the radio frequency (xe2x80x9cRFxe2x80x9d) portion of the electromagnetic spectrum. RF-radiation generated by electronics is a common source of environmental electromagnetic interference (xe2x80x9cEMIxe2x80x9d) that may degrade or impair operation of other electronic devices and circuits exposed to the RF-radiation. Increased use of electronic devices, especially mobile electronic devices, such as cellular phones, has increased environmental EMI levels. Consequently, EMI shields have been incorporated into equipment enclosures to block EMI from interfering with components within equipment enclosures, as well as to shield the environment from EMI generated by components within the enclosure.
Currently, many EMI shields are semi-permanently attached to bezels using fasteners and expensive and time-consuming post-mold heat-taking steps during the manufacturing process. In addition to EMI-shield attachment being slow and expensive, EMI-shield removal is tedious, and the risk of damage to the bezel is high. Recycling of EMI shield/bezel combinations requires the plastic bezel to be separated from the EMI shield, and is therefore expensive and time-intensive because of the semi-permanent post-mold heat-stake attachments. Attachment of EMI shields by semi-permanent, post-mold heat-staking steps also fails to provide an option for consumers to purchase a bezel assembly without a pre-installed EMI shield. Consumers purchasing electronic devices in a configuration not requiring an EMI shield must still purchase an equipment enclosure pre-assembled with an EMI shield to ensure adequate shielding for future upgrades.
Thus, manufacturers, designers, and consumers of electronic devices have recognized the need for a system allowing for simple, easily detachable attachment of an EMI shield to a bezel, and a bezel to an equipment enclosure.
In one embodiment of the present invention, one of more EMI-shield-and-snap-retention features are molded onto the inner lip of a bezel in a single mold. The snap-retention section of the EMI-shield-and-snap-retention feature comprises two guide strips and two ramp-shaped pieces that receive a snap, which is attached to an equipment enclosure. As the bezel reaches a final, flush position against the equipment enclosure, the two guide strips guide the convex tip of the snap up the ramp-shaped pieces. The ramps increase the displacement of the snap, causing a build-up of tension within the snap. When the convex tip of the snap passes over the back edge of the ramp-shaped pieces, displacement of the snap is reduced. Thus, tension is released within the snap, and the tip of the snap stays secured to the back edge of the ramp-shaped pieces.
The EMI-shield-retention section of the EMI-shield-and-snap-retention feature, comprising the two guide strips, partially fastens an EMI shield to the bezel. Each guide-strip further comprises a flanged section and a tapered section. The flanged section extends along the outer edge of the inner lip of the bezel, while the tapered section extends across the inner lip, from the outer edge to the major inner surface of the bezel. As the EMI shield is placed flat along the major inner surface of the bezel, a notch, cut from one edge of the EMI shield, slides around the tapered section of the guide strips, and under the flanged section. The flanged section presses the EMI shield against the major inner surface of the bezel, thus securing a portion of the EMI shield against the bezel. Thus, the embodiment of the present invention embodies a single, molded EMI-shield-and-snap-retention feature incorporating a multiplicity of different functions, thereby reducing tool complexity and cost and improving reliability.